VRII (Variable Rate IV Insulin Infusion) is a reactive tool: it is staff-intensive, finger-prick heavy, and often “playing catch-up.”
Still vital in the acutely unwell when tight glycaemic control is essential (e.g. post-MI: 4–8 mmol/L; acute stroke or peri-op: 4–11 mmol/L).
⚠️ Main risk = hypoglycaemia, especially in sedated or comatose patients ➝ hence stroke units accept slightly higher targets than cardiac units.
Insulin needs vary with stress, illness, nutrition, and resistance ➝ no sliding scale is perfect. Most escalate if glycaemia not controlled.
When stress/illness resolves ➝ transition rapidly back to oral agents (T2DM) or regular insulin (T1DM/new diagnosis).

🧾 Blood Glucose Ranges (UK vs US)

Range	UK (mmol/L)	US (mg/dL)
✅ Normal (fasting)	4.0 – 5.9	72 – 106
✅ Normal (post-meal)	4.0 – 7.8	72 – 140
⚠️ Pre-diabetes (fasting)	6.0 – 6.9	108 – 124
🩸 Diabetes (fasting)	≥ 7.0	≥ 126
⬇️ Hypoglycaemia	< 4.0	< 72
📊 Random diabetes dx	≥ 11.1	≥ 200
⚠️ High hyperglycaemia	20	360
🚨 Severe hyperglycaemia	30	540

💡 Exam Tip: Quote “4–11 mmol/L” as the safe inpatient target, but “4–8 mmol/L” post-MI for tighter control. One small clinical caveat: VRII tables vary a lot between trusts, especially the paired substrate fluid, potassium rules, and escalation thresholds, so keeping “check local guideline” in the heading is exactly right.

💉 Standard VRII Protocol (check local guideline!)

Preparation: 50 units soluble insulin in 49.5 mL 0.9% NaCl via syringe pump. Run alongside 5% dextrose + 40 mmol KCl at 30 mL/hr (unless hyperkalaemic).

Capillary Blood Glucose	mg/dL	VRII Rate	Action
<4.0 mmol/L	<72	🚫 Stop infusion	Treat hypoglycaemia urgently.
4.1–6.0 mmol/L	74–108	1 mL/hr	Continue monitoring.
6.1–8.0 mmol/L	110–144	2 mL/hr	Continue monitoring.
8.1–10.0 mmol/L	146–180	3 mL/hr	Continue monitoring.
10.1–12.0 mmol/L	182–216	4 mL/hr	Continue monitoring.
12.1–14.0 mmol/L	218–252	5 mL/hr	Continue monitoring.
>14.1 mmol/L	>254	6 mL/hr	Use for 2 hours; if glucose remains elevated, check IV line/cannula and call a doctor.

⏩ Transitioning Off VRII

Calculate insulin used in last 12h ➝ double for 24h requirement.
Split: 1/3 as intermediate at 22:00, 2/3 as short-acting with meals.
Switch back to oral therapy (T2DM) or usual regimen (T1DM) as soon as stable.

📊 Monitoring

Check capillary glucose (BM) hourly while on VRII.
Electrolytes: monitor K⁺ closely (risk of hypokalaemia with insulin).
Aim 4–7 mmol/L pre-meal once stabilised.
Document, adjust promptly, and escalate if unstable.

🎓 Patient Education

Never stop insulin when unwell ➝ risk of DKA ⚠️.
Follow “sick-day rules”: maintain hydration, test frequently, seek medical help early.
Warn about hypoglycaemia signs, especially if elderly or with poor awareness.

The content on this website is provided for educational and informational purposes only to support exam preparation (e.g., MLA, MRCP, USMLE) and learning. This is NOT medical advice, diagnosis, treatment, or professional guidance. It does not replace consultation with a qualified healthcare professional, official guidelines (e.g., NICE, GMC, BNF), or supervised clinical practice. Always verify information with current, authoritative sources. Makindo and its contributors accept no liability for any reliance on this content, including errors, omissions, or any resulting harm, loss, or consequences. By using this site, you agree to these terms.

Diabetes Variable Rate Insulin Infusion

📖 Introduction

🧾 Blood Glucose Ranges (UK vs US)

💉 Standard VRII Protocol (check local guideline!)

⏩ Transitioning Off VRII

📊 Monitoring

🎓 Patient Education

Categories